The present invention is generally concerned with mailing machines, including means for feeding sheets therethrough, and more particularly with an improved means for feeding mixed thickness sheets in a mailing machine.
As shown in U.S. Pat. No. 2,934,009, issued Apr. 26, 1962, to Bach, et al. and assigned to the assignee of the present invention, there is described a mailing machine which includes a postage meter and a base on which the postage meter is removably mounted. The postage meter includes a rotary printing drum, for printing postage on a sheet, and a drive gear for the drum. And, the base includes a drive mechanism having an output gear which is disposed in meshing engagement with the drum drive gear when the postage meter is mounted on the base. The drive mechanism includes a single revolution clutch, having a helical spring, for rotating the output gear and thus the drum drive gear, which, in turn, rotates the drum into engagement with a sheet fed to the drum. Each revolution of the clutch, and thus of the drum, is initiated by a sheet engaging a trip lever to release the helical spring for causing the drum to rotate into engagement with the sheet and print a postage value thereon. Moreover, the mailing machine includes structure for feeding the sheet downstream beneath the drum as the drum returns to its home position. Thus the drive mechanism intermittently operates the rotary printing drum in response to a sheet fed thereto engaging the trip lever.
As shown in U.S. Pat. No. 2,871,781 issued Feb. 3, 1959 to Schremfp and assigned to the assignee of the present invention, the mailing machine additionally includes sheet feeding apparatus mounted in the base for feeding sheets downstream in the path of travel. The sheet feeding apparatus includes an impression roller resiliently mounted beneath the postage meter drum to accommodate urging letters of different thickness into printing engagement with the rotating drum.
Although the single revolution clutch structure has been replaced by other intermittently operable drive systems in low volume applications, the sheet feeding and trip structures of the prior art have been retained although experience has shown that the presently available mechanical structures often malfunction and are thus relatively expensive to maintain.
Apart from the above considerations, it has been found that whether or not the sheet feeding and trip structures of the prior art malfunction, customers often misfeed sheets to the machine, most usually by feeding sheets aslant to the edge registration fence provided for properly aligning the sheets with the path of travel in which the sheets are fed to through the machine.
Accordingly, an object of the invention is to replace the sheet feeding structure of the prior art with simplified, easily maintainable and highly reliable sheet feeding structure;
Another object is to provide improved trip structure; and
Another object is to provide improved edge registration structure.